For the Animation projects, we have a total of 7 templates. Of the 7, 3 templates will allow you to set background images and 4 will allow you to set solid color backgrounds.
Here are the templates that will allow you to set and change background:
If you have selected a template that only allows you to set solid background colors, you will not be able to set animated backgrounds for them.
You can choose to go back to the "Theme" section and select a template that supports having an animated background.
